FIG. 1 is a schematic diagram of a network in the existing technology where a mobile terminal communicates with a second device over a wireless local area network. A mobile terminal (Station, abbreviated as STA) 10 is associated with an access point (abbreviated as AP) 12 for accessing a WLAN; a second device 18 may be connected to a forwarding device over a wired network or be directly connected to the forwarding device by using a network cable, where the second device may be a user terminal, for example, a personal computer, or a server in a network. In a wireless local area network (abbreviated as WLAN), a service packet may be forwarded in two manners, namely, local forwarding and tunnel forwarding, where the tunnel forwarding is also referred to as centralized forwarding.
In the case of the local forwarding manner, the STA 10 sends a service packet to the AP 12; the AP 12 converts the service packet into an Ethernet service packet and sends the Ethernet service packet to a port P0 13 of a forwarding device 14; the forwarding device 14 may learn, on the P0 13 port, an address of the STA 10, and sends the Ethernet service packet to the second device 18. If the second device 18 sends a service packet to the STA 10, the forwarding device 14 may send the service packet from the port P0 13 to the STA 10.
In the case of the tunnel forwarding manner, the STA 10 sends a service packet to the AP 12; the AP 12, after converting the service packet into an Ethernet service packet, needs to encapsulate the Ethernet service packet into a tunnel of Control and Provisioning of Wireless Access Points (abbreviated as CAPWAP); the forwarding device 14 sends the encapsulated service packet to an Access Controller (abbreviated as AC) 16; the AC 16 performs tunnel decapsulation to obtain the Ethernet service packet, and then sends the Ethernet service packet to the port P0 13 of the forwarding device 14. The forwarding device 14 may learn, on the port P0 13, an address of the STA 10, and sends the Ethernet service packet to the second device 18. If the second device 18 sends a service packet to the STA 10, the forwarding device 14 may send the service packet from the port P0 13 to the AC 16, thereby performing subsequent packet processing and transmission.
However, for either the local forwarding manner or the tunnel forwarding manner, because of a reason of a wireless side, for example, roaming of the STA, a switchover between active and standby ACs, and the like, a change may occur on a service packet forwarding path from the STA to the second device, thereby producing a problem that a service packet sent by the second device to the STA through a forwarding device cannot reach the STA, which results in low service forwarding efficiency, and reduces service reliability.